Because of the excellent performance and decreasing price of NAND flash, NAND flash-based solid-state drive (SSD) has been widely used as a storage system in consumer electronics. Moreover, modern consumer SSDs usually adopt a multichannel parallel structure. Thus, how to fully utilize the internal parallelism through IO scheduling is a key problem. The existing IO schedulers fail to solve the following: 1) the utilization of flash translation layer information to optimize the internal parallelism is not sufficient; 2) the wear of flash memory is not considered when allocating write requests. This article proposes a Wear-aware Out-of-order Dynamic Scheduling Algorithm (WODSA). First, according to the information of the flash translation layer, the max-parallel-based scheduling strategy is proposed to schedule the read requests to maximize read parallelism. Second, the wear-aware dynamic write allocation strategy is proposed based on the idle/busy state and wear degree of channels and chips. WODSA allocates write requests to channels and chips with less wear preferentially in a maximized parallel manner to achieve write parallelism and active dynamic wear-leveling. Experimental results show that compared with existing IO schedulers and dynamic wear-leveling algorithms, WODSA can improve both the average response time and wear-leveling in block-level and channel-level.

中文翻译：

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基于NAND闪存的消费类电子产品的磨损感知无序动态调度

由于NAND闪存的出色性能和不断下降的价格，基于NAND闪存的固态驱动器（SSD）已被广泛用作消费电子产品中的存储系统。此外，现代消费类SSD通常采用多通道并行结构。因此，如何通过IO调度充分利用内部并行性是一个关键问题。现有的IO调度程序无法解决以下问题：1）利用闪存转换层信息来优化内部并行性是不够的；2）分配写请求时不考虑闪存的磨损。本文提出了一种磨损感知的无序动态调度算法（WODSA）。首先，根据Flash转换层的信息，提出了基于最大并行度的调度策略来调度读取请求以最大化读取并行度。其次，基于空闲/繁忙状态以及通道和芯片的磨损程度，提出了磨损感知动态写分配策略。WODSA优先以最大化的并行方式将写请求分配给损耗较少的通道和芯片，以实现写并行性和主动动态损耗均衡。实验结果表明，与现有的IO调度程序和动态耗损均衡算法相比，WODSA可以在块级和通道级同时改善平均响应时间和耗损均衡。WODSA优先以最大化的并行方式将写请求分配给损耗较少的通道和芯片，以实现写并行性和主动动态损耗均衡。实验结果表明，与现有的IO调度程序和动态耗损均衡算法相比，WODSA可以在块级和通道级同时改善平均响应时间和耗损均衡。WODSA优先以最大化的并行方式将写请求分配给损耗较少的通道和芯片，以实现写并行性和主动动态损耗均衡。实验结果表明，与现有的IO调度程序和动态耗损均衡算法相比，WODSA可以在块级和通道级同时改善平均响应时间和耗损均衡。